I had the same problem, but I wiped everything out and reinstalled fresh. Now I get good battery life.

One thing I did to differently: instead of immediately trying to restore apps from Titanium Backup, I let the market do its thing first. Not sure if that makes a difference or not, but it was the only thing I could point to that I did differently other than downgrade the baseband.

You could also try an alternate kernel. I'm running really smoothly with good battery life on Chevy's ULV 1.0ghz kernel.